Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F291/00—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00
  • C08F291/02—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00 on to elastomers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers

Definitions

• the present invention relates to new fluorinated thermoplastic elastomers having superior mechanical and elastic properties and to the preparation process thereof.
• thermoplastic elastomers are block copolymers consisting of at least a "soft" segment having elastomeric properties and of at least a "hard” segment having plastomeric properties. Therefore, such products combine the typical properties of conventional crosslinked elastomers with those typical of plastomers. With respect to the traditional elastomers, they do not require any vulcanization process, hence they are easily processable and recyclable according to the techniques usually employed for thermoplastic polymers, with apparent both economical and ecological advantages.
• Fluorinated thermoplastic elastomers are known in the art.
• fluorinated block polymers constituted by alternated hard and soft segments, at least one being fluorinated, are described.
• Such products are obtained by radical polymerization of fluorinated monomers in the presence of an iodinated chain transfer agent of formula RI n , wherein R is a fluorinated radical, optionally containing chlorine, having from 1 to 8 carbon atoms, and n is 1 or 2, thus obtaining a first fluorinated polymer segment, with elastomeric or plastomeric characteristics depending on the monomeric composition, having an iodine atom on one or both of the end-groups.
• the Applicant has now surprisingly found that it is possible to obtain new fluorinated thermoplastic elastomers endowed with superior mechanical and elastic properties by introducing into the polymer chain small amounts of a bis-olefin, whose structure is defined hereinunder.
• the obtained products are especially characterized by particularly low compression set values in comparison with the fluorinated thermoplastic elastomers known in the art, having also superior mechanical properties, in particular as regards tensile strength.
• a block polymer is thus obtained, formed by two different types of segments, which still shows at least an iodinated end-group which can be used in a further polymerization stage, in order to introduce in the structure other polymer segments different or even equal to the preceding, with the proviso that in any case blocks of type A (elastomeric) alternated to blocks of type B (plastomeric) are to be obtained (to this purpose see what described in US Patent No. 4,158,678).
• Z is a (per)fluoropolyoxyalkylene radical
• it has preferably the formula: -(Q) p -CF2O-(CF2CF2O) m (CF2O) n -CF2-(Q) p - (II)
• Q is an alkylene or oxyalkylene radical C1-C10
• p is 0 or 1
• m and n are numbers such that the ratio m/n is comprised between 0.2 and 5 and the molecular weight of said (per)fluoropolyoxyalkylene radical is of from 500 to 10,000, preferably from 1,000 to 4,000.
• Such fluorinated olefinic monomers can be also copolymerized with non-fluorinated olefins C2-C8, such as ethylene, propylene, isobutylene.
• the process for preparing the fluorinated thermoplastic elastomers object of the present invention is preferably carried out in aqueous emulsion according to methods well known in the art, in the presence of suitable radical initiators.
• suitable radical initiators can be selected for instance from: inorganic peroxides (for instance alkali metal or ammonium perphosphates, perborates or percarbonates), optionally in combination with ferrous, cuprous or silver salts or other readily oxidable metals; organic peroxides (for instance, disuccinylperoxide, tertbutyl-hydroperoxide, ditertbutyl-peroxide); azocompounds (see US-2,515,628 and US-2,520,338). It is also possible to use organic or inorganic redox systems, such as ammonium persulphate/sodium sulphite, hydrogen peroxide/aminoiminomethansulphinic acid.
• R f -X ⁇ M+ wherein R f is a (per)fluoroalkyl chain C5-C16 or a (per)fluoropolyoxyalkylene chain, X ⁇ is -COO ⁇ or -SO3 ⁇ , M+ is selected from: H+, NH4+, alkali metal ion.
• fluorinated surfactants of formula: R f -X ⁇ M+ wherein R f is a (per)fluoroalkyl chain C5-C16 or a (per)fluoropolyoxyalkylene chain, X ⁇ is -COO ⁇ or -SO3 ⁇ , M+ is selected from: H+, NH4+, alkali metal ion.
• ammonium perfluorooctanoate (per)fluoropolyoxyalkylenes terminated with one or more carboxylic groups, etc.
• iodinated chain transfer agents of formula R f I n are added to the reaction medium, wherein R f is a (per)fluoroalkyl or a (per)fluorochloroalkyl having from 1 to 16 carbon atoms, preferably from 1 to 8 carbon atoms, whereas n is 1 or 2. It is also possible to use as chain transfer agents iodides and/or bromides of alkali or alkaline-earth metals, as described in US Patent 5,173,553. The amount of chain transfer agent to be added is determined according to the molecular weight meant to be achieved and on the effectiveness of the transfer agent itself.
• the amount of bis-olefin to be added to the reaction medium depends on the amount of units deriving therefrom which are desired in the final product, keeping in mind that at the low amounts employed according to the present invention, in practice the whole bis-olefin present in the reaction medium enters the chain.
• step (a) When the step (a) is concluded, the reaction is discontinued, for instance by cooling, and the residual monomers are removed, for instance by heating the emulsion under vigorous stirring.
• the second polymerization step is then carried out, feeding the new monomer mixture and adding new radical initiator.
• chain transfer agent is added, which can be selected from the same iodinated products described above, or from the transfer agents known in the art for fluorinated polymers, such as for instance: ketones, esters or aliphatic alcohols having from 3 to 10 carbon atoms, such as acetone, ethylacetate, diethylmalonate, diethylether, isopropyl alcohol, etc.; hydrocarbons, optionally containing hydrogen, such as chloroform, trichlorofluoromethane, etc.; bis-(alkyl)carbonates wherein the alkyl has from 1 to 5 carbon atoms, such as bis(ethyl) carbonate, bis(isobutyl) carbonate, etc.
• ketones, esters or aliphatic alcohols having from 3 to 10 carbon atoms, such as acetone, ethylacetate, diethylmalonate, diethylether, isopropyl alcohol, etc.
• hydrocarbons optionally containing hydrogen,
• thermoplastic elastomer is isolated from the emulsion by means of conventional methods, such as coagulation by addition of electrolytes or by cooling.
• the polymerization reaction can be carried out in mass or in suspension, in an organic liquid where a suitable radical initiator is present, according to known techniques.
• the polymerization temperature and pressure can vary within wide limits depending on the type of monomers used and on the other reaction conditions. It is generally operated at a temperature of from -20° to 150°C, with a pressure up to 10 MPa.
• thermoplastic elastomers object of the present invention is preferably carried out in aqueous emulsion in the presence of an emulsion, dispersion or microemulsion of perfluoropolyoxyalkylenes, as described in US Patents 4,789,717 and 4,864,006.
• the autoclave was then brought to 80°C and kept at such temperature for the overall duration of the reaction.
• the following mixture of monomers was then fed: VDF 23.5% by moles HFP 61.0% by moles TFE 15.5% by moles so as to bring the pressure to 25 bar.
• the pressure of 25 bar was kept constant for the overall duration of the polymerization by feeding a mixture consisting of: VDF 50.0% by moles HFP 26.0% by moles TFE 24.0% by moles
• the autoclave was then brought to 80°C and kept at such temperature for the overall duration of the reaction.
• the pressure of 25 bar was kept constant for the overall duration of the polymerization by feeding a mixture consisting of: VDF 54.0% by moles MVE 24.0% by moles TFE 22.0% by moles
• the reaction was discontinued by cooling the reactor at room temperature.
• the so obtained latex was heated to 95°C for 30 minutes under stirring at 100 rpm.
• the residual pressure was then discharged and the temperature brought to 80°C.
• VDF was then fed into the autoclave up to a pressure of 30 bar, and 100 ml of a 0.5 g/l APS solution were then added.
• the polymerization was carried out for 197 minutes until a conversion of 560 g of VDF was obtained.
• the autoclave was then cooled, the latex discharged and the polymer coagulated by adding an aluminum sulphate solution (6 g of sulphate per liter of latex). After washing, the so obtained product was dried in oven for 24 hours at 70°C and then characterized as reported in Table 2.
• the polymer monomer composition was determined by 19F-NMR analysis.
• the autoclave was then brought to 80°C and kept at such temperature for the overall duration of the reaction.
• the following mixture of monomers was then fed: VDF 23.0% by moles HFP 65.0% by moles TFE 12.0% by moles so as to bring the pressure to 25 bar.
• the pressure of 25 bar was kept constant for the overall duration of the polymerization by feeding a mixture consisting of: VDF 50.0% by moles MVE 26.0% by moles TFE 24.0% by moles
• the polymerization was carried out for 183 minutes until a conversion of 560 g of the ET/TFE mixture was obtained.
• the autoclave was then cooled, the latex discharged and the polymer coagulated by adding an aluminum sulphate solution (6 g of sulphate per liter of latex). After washing, the so obtained product was dried in oven for 24 hours at 70°C and then characterized as reported in Table 3.
• the polymer monomer composition was determined by 19F-NMR analysis.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Graft Or Block Polymers (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1993
  • 1993-12-29 IT IT93MI002749A patent/IT1265460B1/it active IP Right Grant
• 1994
  • 1994-12-22 US US08/361,660 patent/US5612419A/en not_active Expired - Lifetime
  • 1994-12-23 EP EP94120505A patent/EP0661312B1/fr not_active Expired - Lifetime
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  • 1994-12-29 KR KR1019940038926A patent/KR100360706B1/ko active IP Right Grant
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